Spinning die

ABSTRACT

Spinning nozzle and the production of profiled filaments, threads, bristles or the like in the melt-spinning of a synthetic thermoplastic high molecular weight fiber-forming linear polymer by means of an H-shaped spinning orifice or opening wherein the crossbar flanks are parallel to and the inner flanks of the legbars are perpendicular to the axis of symmetry, the outer flanks of the legbars of the H-shaped orifice being at an angle of at least 5* up to 45* to the corresponding inner flanks.

United States Patent Stapp 1 SPINNING DIE [72] Inventor: Hans Stapp,Momlingen, Germany [73] Assignee: Akzona Incorporated, Asheville, NC.

[22] Filed: Mar. 31, 1970 211 App]. No.2 24,094

[30] Foreign Application Priority Data Apr. 5, 1969 Germany ..G 6913 818[52] US. Cl ..425/461, 264/177 F [51] ...D0ld 3/00, B28h 21/54 [58]Field of Search ..264/177 F; 18/8 SS [56] References Cited UNITED STATESPATENTS 2,373,892 4/1945 Hickey ..264/177F 3,103,264 9/1963 Katan..264/177F Shaw et a1. ..264/177 F Holden ..264/177 F FOREIGN PATENTS ORAPPLICATIONS 1,170,552 11/1969 Great Britain ..264/177 F PrimaryExaminer-Jay H. Woo Atwrney.lohnston, Root, OKeefe, Keil, Thompson andShurtleff 57] ABSTRACT Spinning nozzle and the production of profiledfilaments, threads, bristles or the like in the melt-spinning of asynthetic thermoplastic high molecular weight fiber-forming linearpolymer by means of an H-shaped spinning orifice or opening wherein thecrossbar flanks are parallel to and the inner flanks of the legbars areperpendicular to the axis of symmetry, the outer flanks of the legbarsof the H-shaped orifice being at an angle of at least 5 up to 45 to thecorresponding inner flanks.

9 Claims, 1 Drawing Figure Patented March 21, 1972 3,650,659

INVEN'I'OR: H A N 5 STA P P 0%?? I ATT'YS SPINNING DIE For theproduction of profiled filaments, bristles and the like, a number ofprofiled spinning Openings have been proposed which are more or lesssimilar to the shape of an H. Such H-profiled orifices or openings aresometimes desired as a double-T profile or, if the crossbar orcrossmember is very strongly pronounced in comparison to the height ofthe profile, as I-profiles. 1

Thus, in FIG. 1 of Pat. No. 42,973 of the Office of Invention and PatentMatters of the German Democratic Republic, there is illustrated ashaping or forming nozzle for the continuous drawing ofglass-fiber-reinforced synthetic resin elements in which the nozzle hasa double-T profile. The crossbar flanks or edges of the profiled openingrun parallel to the axis of symmetry which is parallel and midwaybetween these flanks The inner flanks or edges formed by the legs orlegbars projecting from the crossbar (designated by A and C) runperpendicular to the axis of symmetry. The outer flanks or edges ofthese projecting legs run parallel to the inner flanks, i.e., so as tobe also perpendicular to the axis of symmetry through the crossbar.

The inner and outer leg flanks of the I-I-profiled opening shown in FIG.11 of Pat. No. 32,870 of the Office of Invention and Patent Matters ofthe German Democratic Republic likewise run parallel to one another. Atthe points of intersection between the inner leg flanks and the crossbarblanks, bores or enlarged openings are provided in order to assure abetter connection between the individual bands of the molten polymer,the bores providing-an increased feed of the melt at each point ofintersection. A similar construction is followed in the spinningopenings according to FIGS. 5 and 6 of Pat. No. 23,616 of the Office ofInvention and Patent Matters of the German Democratic Republic.

French Pat. No. 1,358,092 likewise illustrates in FIG. 2 an H-shapedprofiled opening in which the inner and outer flanks of the legbarprojections run parallel. The crossbar flanks in this case extendlaterally beyond the outer legbar flanks. The filament cross sections,achieved by means of a spinning nozzle profiled in this manner aremulti-lobed and are strongly dependent on the viscosity of the melt.Even with a shortening of the crossbar flanks, the extruded filamentsexhibit no great similarity to an I i-shape once they are spun anddrawn. A similar conclusion can. be applied to the I-I-profilerepresented in FIG. 21 of Italian Pat. No. 269,130, as well as for thelprofiles of FIGS. l to V of US. Pat. No. 2,945,739, the use of whichleads to bandor ribbonlike products without any preciselydefinedcross-sectional shape.

With the various known H,-, l or double T-types of profiles noted above,it is not possible to spin filaments, bands, bristles or the like frommelts of synthetic fiber-forming linear polymers, such as polyamides,polyesters or the like, with adequate precision or with any assurancethat the products will be uniformly I i-shaped in cross section.

One object of the present invention is to provide a spinning nozzlecapable of yielding a profiled filamentary synthetic thermoplasticpolymer product under otherwise conventional spinning conditions suchthat the profile or cross section of the spun product has a definite anduniform H-shape, i.e., with a clearly defined crossbar andfourprojecting legs or legbars extending approximately perpendicular to thecrossbar at either end thereof. Another object of the invention is toprovide a spinning nozzle which can be used to achieve useful I-I-profiled filaments, bristles or the like of melt-spun and drawnfiber-forming linear polymers. In this respect, the invention has as anobject the process of melt-spinning with the precisely shaped spinningorifice and the resulting product of this process. Otherv objects andadvantages of the invention are explained more fully hereinafter.

In accordance with the invention, it has now been found that one canachieve a uniformly H-shaped filament of the usual fiber-formingthermoplastic polymers by employing in the spinning die a spinningnozzle with a flanked opening defining an H-shapedaextrusion orificehaving a horizontal axis of symmetry through the crossbar of the H, saidcrossbar being formed by flanks of the opening running parallel to saidaxis of symmetry and each projecting legbar of the H being formed by aninner flank running perpendicular to said axis of symmetry and an outerflank positioned at an angle a to said inner flank of at least 5 and notmore than 45, the smallest distance between said inner flank and outerflank of each legbar being approximately equal to the spacing betweenthe parallel flanks of said crossbar.

The invention is more fully illustrated in connection with theaccompanying drawing which provides a highly enlarged plan view of acutaway portion of the face of a nozzle plate or die containing theH-shaped orifice or spinning opening therein.

The exact shape or configuration of the spinning nozzle of the inventionis quite critical in achieving precisely H-shaped filamentary products,but otherwise it is possible to employ conventional melt-spinning anddrawing apparatus and processing conditions which are well known in theart of synthetic filaments or similar extrusion products. Thiscriticality arises due to previous difficulties experienced inattempting to produce relatively fine or thin profiled filaments whichare subject to considerably distortion and reduction in size or shapeduring the spinning and drawing operations. Nevertheless,-in order toachieve a linearly oriented filamentary product, these distortinginfluences cannot be avoided, and the particular shape of the spinningorifice has been found to be of very special importance in achieving auniformly H- shaped product.

All synthetic fiber-forming linear polymers are generally suitable asmelt-spinnable substances for purposes of the invention, and especiallydesirable products are obtained when using conventional polyamides ornylons such as polyhexamethylene adipamide or polycaprolactam and alsolinear saturated polyesters such as polyethylene terephthalate. Otherthermoplastic fiber-forming polymers such as polyacrylonitrile orpolyolefins such as polypropylene may also be used. In spite of the factthat such polymers must be spun as a highly viscous melt, very uniformH-profiled filaments are obtained with a precisely defined crosssection.

Referring now to the drawing, the spinning nozzle of the invention iscontained in the usual nozzle plate or die through which the polymermelt is extruded. Each die normally is furnished with a larger number ofspinning opening or orifices, depending on the size of the extrudedfilaments and capacity of the spinning head, but for convenience onlyone of such openings or orifices has been illustrated.

The H-shaped opening has four projecting legs or legbars as defined bythe inner flanks or edges 1 and the outer flanks or edges 2 connected bythe crossbar or crossmember of the H as defined by the parallel flanksor edges 3,3. The l-l-shaped opening has a horizontal axis of symmetry 4extending through the middle of the crossbar and parallel to thecrossbar flanks 3,3 so that the upper and lower portions of the H-shapedprofile are substantially identical. It is likewise preferable to employan orifice which is symmetrical about a vertical axis positioned midwaybetween the oppositely disposed inner flanks 1 of the legbars.

The inner flanks 1 of the legbars are perpendicular to the crossbarflanks 3,3, i.e., so that the legbars intersect at a right angle to thecrossbar. The outer flanks 2 of the legbars, on the other hand, mustform the angle a with each corresponding inner flank 1 such that 5 a 45.In this respect, it will be noted that the outer flanks 2 of the pair oflegbars on each side of the I-l-shaped opening will taper inwardly tointersect at the horizontal axis of symmetry and form an angle ofintersection of 2a. The opening or orifice is finally closed orcompleted by the end flanks or edges 5 which are preferably in aposition perpendicular to a line 6 bisecting the flank angle at, Le, aline at the angle 11/2 midway between the flanks l and 2. This positionof flanks 5 favors the formation of a true H- profile of the melt-spunpolymer. The smallest distance or spacing b between the inner flank land outer flank 2 of each legbar should be approximately equal to thespacing a between the crossbar flanks 3,3. With this special arrangementor positioning of the inner and outer flanks with respect to each otherin each legbar and with reference to the crossbar, it is possible toextend or impart the desired H-profile to the filamentary product as itis spun and drawn into a final product. Without this preciseconfiguration of the spinning nozzle or orifice, a favorable effect isnot achieved in the formation of an H-profiled product.

It should further be noted that the spacing or distance c betweenoppositely disposed inner flanks l of the legbars and also the length dof these inner flanks are of some importance in achieving an H-profiledstructure. Thus, in order to make certain that the spinning nozzle formsa single definite H- profile structure rather than a number ofrelatively shapeless or nonuniform protruding bands or legs, while onthe other hand also preventing the melt from fusing into a structurewithout any clear hollow space between the inner leg flanks and crossbarflanks, it is desirable to space the crossbar flanks 3 and 3' at adistance a of at least about 0.05 mm. and to also space the oppositeinner leg flanks at a distance of at least about 0.15 mm. The spacing balways remains approximately equal to the spacing a. Finally, it hasbeen recognized as being especially advantageous in accordance with theinvention if the length d of the inner flanks 1 corresponds to about oneto two times the spacing c between oppositely disposed inner flanks.Once these dimensions or limitations are exceeded, especially whenextruding viscous molten polymers, it becomes considerably moredifficult if not impossible to achieve a uniformly and precisely definedH-shaped structure in the final product.

In an especially preferred embodiment of the invention, the spinningnozzle or orifice is employed wherein the flank angle 0 lies betweenabout and By working within these sizes of the flank angle, i.e., theangle between the inner flank l and outer flank 2 of each legbar, theresulting melt-spun structures have a profile or cross section which ismost comparable to the letter H. Each leg of the H is clearly defined asan approximately perpendicular projection extending from the end of'thecrossbar and blending smoothly and uniformly with the adjacent leg atthe same end of the crossbar, all of the legs being substantiallyuniform in shape and size as bandlike protrusions or extensions on auniform bandlike crossbar.

The term filaments" is employed herein as including threads, bristles oreven ribbonlike profiled structures composed of a fiber-forming polymer,such products being especially useful in brushes or similar articlesrequiring relatively flexible but durable filamentary parts withfingerlike or leglike extensions.

ln referring to a horizontal or vertical" axis of symmetry of thespinning orifice and the melt-spun filaments formed thereby, it will berecognized that the orifice as well as the products can assume anyposition or spatial orientation and that these terms are merely usedwith reference to the normally observed position of the letter H, i.e.,where the legs are vertical and the crossbar is horizontal. Thus, theorifices can be placed in any position in the nozzle plate of thespinning apparatus, and although filaments are usually continuously spunin a vertical direction, this is not essential for purposes of theinvention.

Once the filaments are spun and solidified with conventional spinningequipment other than the special nozzle or extrusion orifice, they arepreferably immediately drawn for molecular orientation in accordancewith known principles. They can then be collected on a winding spool orcut to suitable lengths.

ln producing profiled filaments with the spinning nozzle of theinvention, excellent results have been achieved with the orificeillustrated in the drawing, especially when melt a= 0.060 mm.

b= 0.060 mm.

c=0.200 mm.

d= 0.270 mm.

The resulting filamentary products exhibited a highly uniform H-profileover a long continuous spinning run and maintained this profile withinnormal spinning and drawing conditions.

In general, the spinning nozzle of the present invention is especiallyadapted to the production of profiled filaments having a relativelysmall overall dimension. In terms of individual filament size, the finalprofiled products are preferably those with a size of about 1.0 to 20.0denier, preferably 2.0 to 5.0 denier, these sizes being a measure of theweight per unit length as is conventional in the art of syntheticfilaments and textiles. Relatively thick or heavy filaments areespecially useful as bristles for heavy duty brushes or brooms, whilefiner filaments can be used in softer brushes or may also be used inproducing special textile products.

The invention is hereby claimed as follows:

1. In a spinning die for the production of at least one profiledmelt-spun filament of a synthetic thermoplastic high molecular weightfiber-forming linear polymer, the improvement which comprises a spinningnozzle with a flanked opening defining an H-shaped extrusion orificehaving a horizontal axis of symmetry through the crossbar of the H, saidcrossbar being formed by flanks of the opening running parallel to saidaxis of symmetry and each projecting legbar of the H being formed by aninner flank running perpendicular to said axis of symmetry and an outerflank positioned at an angle a to said inner flank of at least 5 and notmore than 45, the smallest distance between said inner flank and outerflank of each legbar being approximately equal to the spacing betweenthe parallel flanks of said cross bar.

2. A spinning die as claimed in claim 1 wherein said angle of the outerflank to the inner flank of each legbar lies between about 10 and 20.

3. A spinning die as claimed in claim 1 wherein the parallel flanks ofthe crossbar are spaced at a distance of more than 0.05 mm. and theoppositely disposed inner flanks of each pair oflegbars are spaced at adistance ofat least about 0.15 mm.

4. A spinning die as claimed in claim 1 wherein the end flank joiningthe inner and outer flanks of each legbar is perpendicular to a linebisecting the flank angle a.

5. A spinning die as claimed in claim 1 wherein the length of the innerflanks of said legbars is about one to two times the 7 distance betweeneach pair of oppositely disposed inner flanks.

6. A spinning die as claimed in claim 2 wherein the parallel flanks ofthe cross bar are spaced at a distance of more than 0.05 mm. and theoppositely disposed inner flanks of each pair oflegbars are spaced at adistance ofat least about 0.15 mm.

7. A spinning die as claimed in claim 6 wherein the length of the innerflanks of said legbars is about one to two times the distance betweeneach pair of oppositely disposed inner flanks.

8. A spinning die as claimed in claim 1 wherein the overall dimensionsof said extrusion orifice are adapted to produce a melt-spun and drawnthermoplastic, fiber-forming linear polymer having a size ofabout 1.0 to20.0 denier.

9. A spinning die as claimed in claim 2 wherein the overall dimensionsof said extrusion orifice are adapted to produce a melt-spun and drawnthermoplastic, fiber-forming linear polymer having a size of about 2.0to 5.0 denier.

1. In a spinning die for the production of at least one profiledmelt-spun filament of a synthetic thermoplastic high molecular weightfiber-forming linear polymer, the improvement which comprises a spinningnozzle with a flanked opening defining an Hshaped extrusion orificehaving a horizontal axis of symmetry through the crossbar of the H, saidcrossbar being formed by flanks of the opening running parallel to saidaxis of symmetry and each projecting legbar of the H being formed by aninner flank running perpendicular to said axis of symmetry and an outerflank positioned at an angle Alpha to said inner flank of at least 5*and not more than 45*, the smallest distance between said inner flankand outer flank of each leGbar being approximately equal to the spacingbetween the parallel flanks of said cross bar.
 2. A spinning die asclaimed in claim 1 wherein said angle of the outer flank to the innerflank of each legbar lies between about 10* and 20*.
 3. A spinning dieas claimed in claim 1 wherein the parallel flanks of the crossbar arespaced at a distance of more than 0.05 mm. and the oppositely disposedinner flanks of each pair of legbars are spaced at a distance of atleast about 0.15 mm.
 4. A spinning die as claimed in claim 1 wherein theend flank joining the inner and outer flanks of each legbar isperpendicular to a line bisecting the flank angle Alpha .
 5. A spinningdie as claimed in claim 1 wherein the length of the inner flanks of saidlegbars is about one to two times the distance between each pair ofoppositely disposed inner flanks.
 6. A spinning die as claimed in claim2 wherein the parallel flanks of the cross bar are spaced at a distanceof more than 0.05 mm. and the oppositely disposed inner flanks of eachpair of legbars are spaced at a distance of at least about 0.15 mm.
 7. Aspinning die as claimed in claim 6 wherein the length of the innerflanks of said legbars is about one to two times the distance betweeneach pair of oppositely disposed inner flanks.
 8. A spinning die asclaimed in claim 1 wherein the overall dimensions of said extrusionorifice are adapted to produce a melt-spun and drawn thermoplastic,fiber-forming linear polymer having a size of about 1.0 to 20.0 denier.9. A spinning die as claimed in claim 2 wherein the overall dimensionsof said extrusion orifice are adapted to produce a melt-spun and drawnthermoplastic, fiber-forming linear polymer having a size of about 2.0to 5.0 denier.